Clamping device for paper cutting machines



Feb.v 24,` 1970 w..K-RUG ETAL CLAMPNG DEVICE FOR PAPER CUTTING MACHINESFiled llay 23, 1967 M n m :um E u rO WMM/m M mw wm Y, B

United States Patent O 3,497,203 CLAMPING DEVICE FOR PAPER CUTTINGMACHINES Wilhelm Krug and Ludwig Priester, both of 13-17Schickhardtstrasse, 7460 Balingen, Germany Filed May 23, 1967, Ser. No.640,540 Int. Cl. Bb 5/08 U.S. Cl. 269-236 9 Claims ABSTRACT OF THEDISCLOSURE This invention concerns a clamping device for paper cutter inwhich a single hand-operated lever controls the vertical movement of apressure bar. The lever has an eccentric cam that bears against abearing member having a surface that matches the contour of the cam andis connected by a pivot pin to a bar which in turn is connected throughtriangular levers to the pressure bar. The triangular levers are alsopivoted in the xed portion of the structure to produce a reaction forcethat causes the pressure bar to move downward when the lever is pivotedone Way and to move upward when the lever is pivoted in the oppositedirection. In either position of the lever, it is held fast againstundesired movement and it provides a fast-operated pressure devicecapable of achieving high pressures and also of applying the pressureand releasing the pressure rapidly.

This invention relates to a clamping device for paper cutters, and moreparticularly to a clamping device that may be rapidly operated to clamppaper in place.

In clamping devices for paper cutters, in addition to preventing thematerial to be cut from being moved away from the cutting knife, it isnecessary to keep the paper in its proper position during the entirecutting cycle. Because the positioning and holding of the paper by handis unsafe, it is normally necessary to use a clamping device or aclamping plate which is disposed on top of the paper and pressed againstit during the cutting cycle so that the paper is securely held betweenthe cutting table and the clamping piece.

Previously known clamping plates are usually operable by a clamp spindleto raise and lower the clamping plate and to provide the desiredpressure by tightening the spindle. These prior systems are cumbersomeand slow because of the necessity of lengthy turning of the spindlewheel or similar device.

In addition to the spindle method, levers have been used to raise orlower the clamping piece and although this construction is very simple,it does not guarantee that the clamping pressure will be properlymaintained during the entire cutting cycle. In addition there is thepossibility of using hydraulic clamping means which allows for fast andeasy clamping action and ready adjustment of pressure applied to thematerial to be cut, however, such hydraulic devices are relativelycomplicated and expensive and are only economical for use on largemachines.

It is an object of this invention to provide a clamping device for apaper cutting machine that provides for constant pressure to bemaintained on the material to -be cut during the entire cutting cycleand at the same time provides for fast and facile clamping.

ICC

A further object of this invention is to provide such a clamping devicethat provides for a mechanical adv'lntage for manually clamping thematerial to be cut in p ace.

It is an additional object of this invention to provide such a paperclamp that is automatically retained in the clamped position.

It is another object of this invention to provide such a clamping devicethat is relatively inexpensive to manufacture and simple to operate.

It `has been found that the foregoing objects and other advantages canbe readily obtained in a clamping device for paper cutting machineshaving a housing and a clamping plate movably mounted on the housing tohold paper in a fixed position for cutting. A manually actuatable leveris operably connected to the clamping plate to provide a mechanicaladvantage for securely positioning the clamping plate in engagement withthe paper to be cut. Linkage means is connected to the clamping plateand is operable by the lever for moving the clamping plate relative tothe housing. Cam means are provided to be operable by the lever to giveadditional mechanical advantage for operation of the clamping device.The cam means is engaged with the linkage means for imparting movementthereto to position the clamping plate in engagement with the paper tobe cut.

The linkage means may have a bearing member upon which the cam means isslidable to move the linkage means and the clamping plate upon actuationof the lever. In addition the bearing member is adapted to befrictionally retained by the cam means in order to hold the linkagemeans in a fixed position so that the clamping plate is retainedsecurely in engagement with the paper to be cut. The bearing member ispivotally mounted on the linkage means and has a bearing surface adaptedt0 be slidable on and to frictionally engage a cooperating surface ofthe cam means. Desirably, the bearing surface is configured to conformto the cooperating surface of the cam means for at least one half of thearea of the bearing surface.

The cam means may be in the form of an eccentric cam rotatable relativeto the housing and frictionally engageable with the linkage means. Thecam member may have a surface defining a portion of a circle and beeccentrically mounted for rotation on the same axis as the lever toprovide an additional mechanical advantage for operation of the clampingdevice.

The linkage means in the disclosed embodiment has an actuating memberengageable by the cam means and connected to a second lever which ispivotally mounted on the housing and operably connected to the clampingplate. A pair of second levers may be connected to opposite ends of theactuating member and connected to the clamping plate by a pair ofpivotable links in order to impart the force of the manually operablelever and cam means to the clamping plate.

Other objects and advantages will be readily apparent from the followingdetailed description and the attached drawings wherein:

FIGURE 1 is a fragmentary side elevation View illustrating the clampingdevice of this invention for use with paper cutting machines with theparts illustrated in the starting position in solid line and in theclamped position in phantom line.

FIGURE 2 is an enlarged fragmentary view of the bearing member and camof the clamping device illustrated in FIGURE 1.

Referring now to the drawing there is illustrated in FIGURE 1 theclamping device of this invention for paper cutters having a clampingplate, generallydesignated by the reference numeral 1, shown in itsupper or initial position with its lower edge 2 positionedfor engagementwith paper (not shown) to be cut upon move ment in the direction of thearrow 4. The clamping plate 1 is mounted for sliding movement by a pairof projecting guide bars 3 mounted on opposite ends of the clampingplate 1 and partially disposed in grooves in a pair of cooperatingstationary support blocks 5 that form part of a stationary housing.

In order to move the clamping plate 1 in the direction of the arrow 4,thereA is provided a generally semicircular shaped cam 6 which iseccentrically mounted for pivoted movement on the shaft 7 which issupported in a xed position on the stationary housing. The cam 6 ismovable by means of a lever 8 which is xedly attachedvthereto byconventional fastening means and also pivotally mounted on the shaft 7for movement in the direction of the arrow 9.

To translate the clamping plate 1 by movement of the eccentric cam 6there is provided a movably mounted actuating bar 10 that is connectedat opposite ends 11 to a pair of toggle linkages each connected to theclamping plate 1. Each of the toggle linkages has a triangular shapedlever 13 rotatably mounted on a pivot pin 12 which is supported on thestationary housing. The lever 13 is mounted on the pin 12 on a irst apexand is rotatably attached to the bar 10 at a second apex.

A pair of links 14 are each pivotally mounted at their lower portions onthe ends 15 of the clamping plate 1 and their opposite ends are eachattached to the third apex of the triangular levers 13. The levers 13are shaped so that there is a greater distance between the pivot pin 12and the third apex connected to the links 14 than the distance betweenthe pivot pin 12 and the secondvapex connected to the bar 10 to providefor the desired movement of the clamping plate 1.

The actuating bar 10 has a protruding arm 16 which is positioned closerto one end 11 than to its opposite end and carries a bearing member 17made of resistant material which is pivotally mounted thereon. Thebearing member 17 has a surface 18 which engages a surface 19 of theeccentric cam 6, and as illustrated in FIGURE 2, the surface 18 is onlycurved over a portion of its area as it becomes flat in the areaindicated by the straight line 21. This configuration of the surface 18provides for a desirably smooth and effective operation of the eccentriccam 6 and in addition, provides a bearing surface between the eccentriccam and the bearing member 17 that is large enough to provide a retardngeffect so that the lever 8 and the clamping plate 1 are retained in thedesired position.

When it is desired to lower the clamping plate 1 in the direction of thearrow 4, towards paper (not shown) to be retained in the position forcutting, the hand lever 8 with the eccentric cam 6 is moved in adirection of the arrow 9. As a consequence of the action of theeccentric cam 6, the bearing member 17 is forced in the direction of thearrow 22 which causes a movement of the actuating bar 10 in thedirection of the arrow 23. As a result the levers 13 are pivoted in thedirection of the arrow 24 which causes a lowering of the links 14 andthe clamping plate 1 into the clamping position illustrated in dottedline in FIGURE 1 for holding paper (not shown) securely in position forcutting. Because of the particular dimensions of the lever 8, bar 10,the pair of levers 13 and the links 14, a mechanical advantage isprovided to apply a larger force than that applied manually to the lever8 for effectively securing the paper to be cut in a tixed position.

When it is desired to raise the clamp in order to release the materialthat has been cut, the hand lever 8 is swung in a direction opposite tothe arrow 19 so that the bearing piece 17 is released from contact withthe actuating bar 10. A tension spring 25 which is fastened on one endto the stationary housing and on its other end to the bar 10 biases thebar 10 together with the pair of levers 13 and the links 14 into theinitial position, illustrated in solid line in FIGURE 1, thereby raisingthe clamp 1 into its upper position and releasing the paper that hasbeen cut.

Accordingly, the clamping device of this invention provides formaintaining a constant pressure on the material to be cut during theentire cutting cycle and at the same time provides for fast and facileclamping action. In addition the clamping device furnishes a mechanicaladvantage for manually clamping the material to be cut and at the sametime provides for automatically retaining the clamping plate in theclamped position. Further, the clamping device of this invention isrelatively inexpensive to manufacture and is simple to operate.

It will be understood that the foregoing description with the details ofexemplary structure is not to be construed in any way to limit theinvention, but that modiications may be made thereto without departingfrom the scope of the invention as set forth in thefollowing claims.

Having thus described the invention, we claim:

1. A clamping device for paper cutting machines comprising: a housing, alinearly movable clamping plate mounted on said housing to hold paper ina xed position for cutting; a manually actuatable lever operablyconnected to said clamping plate providing a mechanical advantage forsecurely positioning said clamping plate in engagement with paper to becut; linkage means comprising a plurality of related elements connectedto said clamping plate and operable by said lever for moving saidclamping plate relative to said housing; and cam means operable by saidlever providing an additional mechanical advantage for operation of saidclamping device, said cam means being engaged with said linkage meansfor imparting movement thereto to position said clamping plate inengagement with the paper to be cut.

2. The clamping device of claim 1 wherein said linkage means has abearing member upon which said cam means is slidable to move saidlinkage means and said clamping plate upon actuation by said lever, andwherein said bearing member frictionally retains said cam means to holdsaid linkage means in a fixed position so that said clamping plate isretained securely in engagement with the paper to be cut.

3. The clamping device of claim 2 wherein said bearing member ispovotally mounted on said linkage means and has a bearing surfaceadapted to be slidable on and to frictionally engage the cooperatingsurface of said cam means.

4. The clamping device of claim 3 wherein said bearing surface isconfigured to conform to the cooperating surface of said cam means forat least one half of the area of said bearing surface.

5. The clamping device .of claim 1 wherein said cam means has aneccentric cam member rotatable relative to said housing and frictionallyengageable with said linkage means.

6. The clamping device of claim 5 wherein said cam member has a surfacedefining a portion of a circle and is eccentrically mounted on the sameaxis as said lever.

7. The clamping device of claim 1 wherein said linkage means has anactuating member engageable by Said cam means and which is connected toa second lever pivotally mounted on said housing and operably connectedto said clamping plate.

8. The clamping device of claim 7 wherein a pair of said second leversare connected to opposite ends of said actuating member and wherein saidsecond levers are connected to said clamping plate by a pair ofpivotable links.

9. A clamping device for paper cutting machines comprising: a housing; aclamping plate movably mounted on said housing to hold paper in a fixedposition for cutting; a manually actuatable lever pivotally mounted onsaid housing and operably connected to said clamping plate providing amechanical advantage for securely positioning said clamping plate inengagement with paper to be cut; an eccentrically mounted cam rotatableby said lever providing an additional mechanical advantage for opera-ltion of said clamping device; and linkage means comprising a pluralityof related elements connected to said clamping plate, one of saidelements comprising a bearing member pivotally mounted thereon adaptedto be slidable UNITED STATES PATENTS 4/1867 Morse 269-235 X 3/1941McKenna 269-229 10 ROBERT C. RroRDoN, Primary Examiner D. R. MELTON.Assistant Examiner

